Demulsifier for oil exploitation and preparation method thereof

Abstract

The invention relates to a demulsifier for petroleum exploitation and a preparation method thereof, and belongs to the technical field of demulsifiers for petroleum. The preparation method of the demulsifier for petroleum exploitation comprises the following steps: slowly adding silicon dioxide into mixed acid, stirring at a controlled temperature, removing impurities, and drying to obtain a pretreated product; stirring and mixing a silane coupling agent and ethyl acetate, adding sorbic aldehyde for constant-temperature reaction, cooling to room temperature, centrifuging, putting into absolute ethyl alcohol, adding the pretreated product for ultrasonic dispersion, heating and stirring, removing impurities, drying in vacuum, putting into deionized water for mixing, stirring at a high speed, adding acrylamide and benzyl methacrylate for stirring and mixing uniformly, adding an initiator for heating and stirring, and cooling to room temperature; and continuously heating and stirring, cooling, adjusting the pH value, and granulating in a granulator, thereby obtaining the product. The demulsifying agent provided by the invention has excellent performance in the aspect of treating oilfield produced liquid. The water treatment agent can quickly play a role, and the treatment effect is further improved along with the increase of the dosage, so that the water phase is clearer.

Description

Technical Field

[0001] The present invention belongs to the technical field of demulsifiers for petroleum, and relates to a demulsifier for oil production and its preparation method. Background Art

[0002] A large amount of produced fluid in oilfields exists in the form of oil-in-water (O / W) emulsions. Inverse demulsifiers play a crucial role in the treatment of produced fluid in oilfields. In the actual produced fluid treatment process, the inverse demulsifier is added to the three-phase separator, and its main function is to promote the efficient separation of O / W emulsions. It can change the interfacial properties between oil droplets and the aqueous phase in the emulsion, reduce the interfacial tension, and prompt the oil droplets to collide and coalesce with each other, thereby achieving the purpose of oil-water separation.

[0003] The existing patent publication number: CN104560130A discloses a preparation method of a petroleum demulsifier. Acrylic acid, propylene glycol, and dimethyl adipate are added to a reaction kettle, potassium hydroxide and trimethylolpropane are added, the air in the reaction kettle is replaced with an inert gas, then the temperature is raised and stirred, and then vacuum is drawn, then the temperature is raised again and epichlorohydrin and diphenylmethane diisocyanate are added, and stirring reaction is continued to obtain reactant one; then potassium hydroxide, propylene glycol-based polyether, 1,3-butadiene, and reactant one are added to the reaction kettle, the temperature is raised and stirred under the protection of an inert gas, then the temperature is raised again and stirring reaction is continued, and the temperature is lowered to room temperature to obtain reactant two; then polyethylene glycol, polyvinyl formal, methanol, and deionized water are added to the reaction kettle, heated and reacted under vacuum conditions, and then the temperature is lowered to room temperature to obtain reactant three; finally, reactant two and reactant three are mixed, heated and stirred to obtain the demulsifier; the demulsifier obtained by the method of the invention can play a good demulsifying role within a wide temperature range. However, traditional demulsifiers (such as polyoxyethylene polyoxypropylene block copolymers, quaternary ammonium salts) face problems such as low demulsification efficiency, insufficient temperature and salt tolerance, and narrow application range. Summary of the Invention

[0004] The purpose of the present invention is to provide a demulsifier for oil production and its preparation method. The demulsifier of the present invention performs excellently in treating produced fluid in oilfields. It can quickly exert its efficacy, and with the increase of the dosage, the treatment effect is further improved, making the aqueous phase clearer. This demulsifier not only has an economical dosage and remarkable treatment effect, but also has a simple production process and is convenient for large-scale production. Therefore, in the field of treating produced fluid in oilfields, it has great application potential and broad market prospects.

[0005] The purpose of the present invention can be achieved through the following technical solutions: A preparation method of a demulsifier for oil production includes the following steps: Step 1: Add silicon dioxide to the mixed acid, control the temperature and stir, centrifuge, wash, and dry to obtain a pretreated product; Step 2: Stir and mix the silane coupling agent and ethyl acetate, add sorbic aldehyde for reaction, cool, centrifuge, place in absolute ethanol, add the pretreated product for ultrasonic dispersion, heat and stir, filter, wash, and dry to obtain an intermediate product; Step 3: Mix the intermediate product and water, stir at high speed, add acrylamide and benzyl methacrylate and stir, add an initiator and raise the temperature for stirring, continue to raise the temperature for stirring, cool down, adjust the pH, and granulate in a granulator to obtain the product.

[0006] As a preferred technical solution of the present invention, the above preparation method includes the following steps: Step 1: Slowly add silicon dioxide to the mixed acid and stir while controlling the temperature, centrifuge and wash until neutral, and dry to obtain a pretreated product; Step 2: Stir and mix the silane coupling agent and ethyl acetate, add sorbic aldehyde for constant-temperature reaction, cool to room temperature, centrifuge, place in absolute ethanol, add the pretreated product for ultrasonic dispersion, heat and stir, filter, wash with alcohol, and vacuum dry to obtain an intermediate product; React the amino group of the silane coupling agent with the aldehyde group of sorbic aldehyde, and then the siloxane bond of the silane coupling agent reacts with the hydroxyl group on the surface of silicon dioxide to obtain an intermediate product; The reaction formula is: 。

[0007] Step 3: Under an inert atmosphere, mix the intermediate product and deionized water, stir at high speed, add acrylamide and benzyl methacrylate and stir evenly, add an initiator and raise the temperature for stirring, continue to raise the temperature for stirring, cool down, adjust the pH value, and granulate in a granulator to obtain the product. Under the action of the initiator, use the alkenyl group of sorbic aldehyde in the intermediate product as the polymerization site to carry out alkenyl polymerization reaction with acrylamide and benzyl methacrylate.

[0008] As a preferred technical solution of the present invention, in Step 1, the mixed acid is composed of concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 1:0.5 - 1.5, and the temperature-controlled stirring is carried out at 30 - 50 °C for 2 - 3 h.

[0009] As a preferred technical solution of the present invention, in Step 1, the drying is carried out at 110 °C for 1.5 - 2.0 h, and the dosage ratio of silicon dioxide to the mixed acid is 1.0 - 1.2 g:25 - 30 mL.

[0010] As a preferred technical solution of the present invention, in Step 2, the silane coupling agent is N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane.

[0011] As a preferred technical solution of the present invention, in step two, the constant-temperature reaction is carried out at 50 - 62 °C for 4 - 6 h, the ultrasonic dispersion is carried out at a power of 200 - 300 W for 30 - 45 min, the heating and stirring is carried out at a temperature of 50 - 60 °C for 4 - 6 h, and the washing with alcohol is carried out by washing 3 times with absolute ethanol.

[0012] As a preferred technical solution of the present invention, in step two, the mass ratio of the silane coupling agent, ethyl acetate, sorbic aldehyde, absolute ethanol and the pretreated product is 10 - 13:40 - 50:18 - 25:60 - 80:12 - 14.

[0013] As a preferred technical solution of the present invention, in step three, the high-speed stirring is carried out at 1000 - 1200 rpm for 5 - 8 min, the temperature-rising stirring is carried out at 50 - 60 °C for 1.0 - 1.5 h, the continued temperature-rising stirring is carried out at 80 - 90 °C for 0.5 - 1.0 h, the temperature reduction is to reduce the temperature to 40 - 50 °C, the pH value adjustment is to adjust the pH value to 7, and the particle size after granulation is 1 - 2 mm.

[0014] As a preferred technical solution of the present invention, in step three, the mass ratio of the intermediate product, deionized water, acrylamide, benzyl methacrylate and the initiator is 3.0 - 3.5:40 - 50:14 - 16:21 - 26:2.4 - 3.0.

[0015] As a preferred technical solution of the present invention, in step three, the initiator is composed of an oxidizing persulfate and a reducing sulfur-containing salt; the mass ratio of the oxidizing persulfate to the reducing sulfur-containing salt is 2:1; the oxidizing persulfate is one or more of ammonium persulfate, potassium persulfate and sodium persulfate; the reducing sulfur-containing salt is one or more of sodium bisulfite, sodium sulfite and sodium thiosulfate.

[0016] The present invention discloses a demulsifier for oil extraction prepared by the above preparation method.

[0017] The beneficial effects of the present invention: The demulsifier of the present invention performs excellently in treating oilfield produced fluids. It can quickly exert its efficacy, and with the increase of the dosage, the treatment effect is further improved, making the aqueous phase clearer. This demulsifier not only has an economical dosage and significant treatment effect, but also has a simple production process, which is convenient for large-scale production. Therefore, in the field of treating oilfield produced fluids, it has great application potential and broad market prospects.

[0018] In the preparation of the demulsifier for oil exploitation, silica is acidified by a mixed acid to improve the degree of its surface hydroxylation, thereby affecting the grafting of silane; the double amino groups of the silane coupling agent and sorbic aldehyde introduce hydrophobic chain segments to adjust the hydrophilic-lipophilic balance and at the same time bridge with silica; acrylamide increases hydrophilicity and adsorption force, and benzyl methacrylate enhances hydrophobicity. Each component jointly affects the efficiency of the demulsifier in destroying the stability of the oil-water emulsion by regulating the balance of hydrophilic and hydrophobic groups, the interfacial adsorption ability and the molecular chain bridging effect in the molecular structure. Description of the Drawings

[0019] Figure 1 It is the infrared spectrogram of the intermediate product in Example 1.

[0020] Figure 2 It is the infrared spectrogram of the demulsifier in Example 1. Detailed Embodiments

[0021] To further illustrate the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following combines examples to detail the specific embodiments, structures, features and their effects according to the present invention as follows.

[0022] Example 1 A preparation method of a demulsifier for oil exploitation includes the following steps: Step 1: Slowly add silica to the mixed acid, stir at 30°C for 2 h, centrifuge to obtain solid matter, wash it with deionized water until the surface is neutral, and dry it at 110°C for 1.5 h to obtain a pretreatment product; In Step 1, the mixed acid is composed of concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 1:1, and the dosage ratio of silica to the mixed acid is 1.0 g:25 mL; Step 2: Stir and mix the silane coupling agent and ethyl acetate, add sorbic aldehyde, react at 50°C for 4 h, cool to room temperature, centrifuge, place it in absolute ethanol, add the pretreatment product, ultrasonically treat it at a power of 200 W for 30 min, stir at a temperature of 50°C for 4 h, filter, wash it 3 times with pure ethanol, and vacuum dry it at 80°C to constant weight to obtain an intermediate product; Figure 1 The absorption peak of Si-O-Si in silica is at the position of 1088 cm -1 The position of, 1647 cm -1 Is the absorption peak of the C=N bond. It is the Schiff base reaction between the amino group of N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane and the aldehyde group of sorbic aldehyde, generating the C=N bond. 1565 cm -1 Is the characteristic peak of the alkenyl -C=C- in sorbic aldehyde.

[0023] In Step 2, the silane coupling agent is N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane, and the mass ratio of the silane coupling agent, ethyl acetate, sorbic aldehyde, absolute ethanol and the pretreated product is 10:40:18:60:12; Step 3: Under an inert atmosphere, mix the intermediate product with deionized water, then stir at 1000 rpm for 5 min, add acrylamide and benzyl methacrylate and stir for 20 min, add the initiator and stir at 50 °C for 1.0 h, stir at 80 °C and 300 rpm for 0.5 h, cool down to 40 °C, adjust the pH value to 7, granulate in a granulator, and then sieve to obtain a demulsifier with an average particle size of 1 mm; Figure 2 The absorption peak of Si-O-Si in silica is at 1061 cm -1 at the position, and 1646 cm -1 is the absorption peak of the C=N bond, and 1551 cm -1 The alkenyl peak of sorbic aldehyde at [position] is significantly weakened because the alkenyl group has undergone a polymerization reaction with acrylamide and benzyl methacrylate. The characteristic peak of the benzene ring of benzyl methacrylate is at 1417 - 1478 cm -1 and the absorption peak of the -C=O- bond in benzyl methacrylate is at 1718 cm -1 ; the absorption peak of the carbonyl -C=O- in the amide bond of acrylamide is at 1752 cm -1

[0024] In Step 3, the mass ratio of the intermediate product, deionized water, acrylamide, benzyl methacrylate and the initiator is 3.0:40:14:21:2.4, and the initiator is composed of ammonium persulfate and sodium bisulfite in a mass ratio of 2:1.

[0025] Example 2 A preparation method of a demulsifier for oil extraction includes the following steps: Step 1: Slowly add silica to the mixed acid and stir at 40 °C for 2.5 h, centrifuge to obtain the solid, wash it with deionized water until the surface is neutral, and dry it at 110 °C for 1.8 h to obtain the pretreated product; In Step 1, the mixed acid is composed of concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 1:1.2, and the dosage ratio of silica to the mixed acid is 1.1 g:28 mL; Step 2: Stir and mix the silane coupling agent and ethyl acetate, add sorbic aldehyde and react at 56 °C for 5 h, cool to room temperature, centrifuge, place it in absolute ethanol, add the pretreated product and ultrasonicate at 250 W for 38 min, stir at 55 °C for 5 h, filter, wash it 3 times with pure ethanol, and vacuum dry it at 80 °C to constant weight to obtain the intermediate product; ​In Step 2, the silane coupling agent is N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane, and the mass ratio of the silane coupling agent, ethyl acetate, sorbic aldehyde, absolute ethanol and the pretreated product is 12:45:22:70:13; Step 3: Under an inert atmosphere, mix the intermediate product with deionized water, then stir at 1100 rpm for 6 min, add acrylamide and benzyl methacrylate and stir for 20 min, add the initiator and stir at 55 °C for 1.2 h, stir at 85 °C and 300 rpm for 0.8 h, cool down to 45 °C, adjust the pH value to 7, granulate in a granulator, and sieve to obtain a demulsifier with an average particle size of 1.5 mm; In Step 3, the mass ratio of the intermediate product, deionized water, acrylamide, benzyl methacrylate and the initiator is 3.2:45:15:24:2.7, and the initiator is composed of ammonium persulfate and sodium bisulfite in a mass ratio of 2:1.

[0026] Example 3 A preparation method of a demulsifier for oil exploitation includes the following steps: Step 1: Slowly add silicon dioxide to the mixed acid and stir at 50 °C for 3 h, centrifuge to obtain the solid, wash it with deionized water until the surface is neutral, and dry it at 110 °C for 2.0 h to obtain the pretreated product; In Step 1, the mixed acid is composed of concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 1:1.5, and the dosage ratio of silicon dioxide to the mixed acid is 1.2 g:30 mL; Step 2: Stir and mix the silane coupling agent and ethyl acetate, add sorbic aldehyde and react at 62 °C for 6 h, cool to room temperature, centrifuge, place it in absolute ethanol, add the pretreated product and ultrasonicate at 300 W for 45 min, stir at 60 °C for 6 h, filter, wash it 3 times with pure ethanol, and vacuum dry at 80 °C to constant weight to obtain the intermediate product; In Step 2, the silane coupling agent is N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane, and the mass ratio of the silane coupling agent, ethyl acetate, sorbic aldehyde, absolute ethanol and the pretreated product is 13:50:25:80:14; Step 3: Under an inert atmosphere, mix the intermediate product with deionized water, then stir at 1200 rpm for 8 min, add acrylamide and benzyl methacrylate and stir for 20 min, add the initiator and stir at 60 °C for 1.5 h, stir at 90 °C and 300 rpm for 1.0 h, cool down to 50 °C, adjust the pH value to 7, granulate in a granulator, and sieve to obtain a demulsifier with an average particle size of 2 mm; In Step 3, the mass ratio of the intermediate product, deionized water, acrylamide, benzyl methacrylate, and initiator is 3.5:50:16:26:3.0, and the initiator is composed of ammonium persulfate and sodium bisulfite in a mass ratio of 2:1.

[0027] Comparative Example 1 Compared with Example 3, the difference in Comparative Example 1 is that Step 1 is not carried out, and silica is used instead of the pretreatment product in Step 2, and the rest are the same.

[0028] Comparative Example 2 Compared with Example 3, the difference in Comparative Example 2 is that 2-hexenal is used instead of sorbic aldehyde, and the rest are the same.

[0029] Comparative Example 3 Compared with Example 3, the difference in Comparative Example 3 is that sorbic aldehyde is not used, and the rest are the same.

[0030] Comparative Example 4 Compared with Example 3, the difference in Comparative Example 4 is that γ-aminopropyltriethoxysilane is used instead of N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane, and the rest are the same.

[0031] Comparative Example 5 Compared with Example 3, the difference in Comparative Example 5 is that acrylamide is used instead of benzyl methacrylate, and the rest are the same.

[0032] The demulsifiers prepared in Examples 1-3 and Comparative Examples 1-5 were respectively subjected to the following tests, and the test results are shown in Table 1.

[0033] Determination of oil content in the aqueous phase: According to SY / T 5797-1993, the oil content in the aqueous phase is 1485 mg / L, the dosage of the demulsifier is 50 mg / L and 100 mg / L, the temperature is 70 °C, and the test time is 10 min.

[0034] Table 1 Test Results

[0035] It can be seen from the test results in Table 1 that compared with Comparative Examples 1-5, in Examples 1-3, the surface of silica is etched through oxidation and acidification to increase the surface active sites. The mixed acid provides a strong acidic environment and has oxidizing properties. The synergistic effect of concentrated sulfuric acid and concentrated nitric acid can adjust the chemical properties of the silica surface, which is beneficial to the subsequent silane graft modification to form stable Si-O-Si bonds and ensure the structural integrity of the intermediate product. If the acidification is insufficient, the grafting amount of the coupling agent is small, the molecular weight and crosslinking degree of the demulsifier decrease, affecting the stability and demulsification effect of the demulsifier. After the amino group of the silane coupling agent reacts with sorbic aldehyde, a hydrophobic carbon chain segment can be introduced. Then, the grafting with silica can enhance the inorganic-organic hybrid structure of the demulsifier. If the number of amino groups is insufficient, the crosslinking degree of the intermediate product will decrease, and the molecular chain flexibility will be poor, affecting the adsorption ability of the demulsifier at the oil-water interface. The grafted sorbic aldehyde structure can serve as a flexible chain segment of the intermediate product and copolymerize with acrylamide and benzyl methacrylate in the polymerization reaction in Step 3, affecting the molecular weight and chain segment distribution of the polymer. Benzyl methacrylate is a hydrophobic monomer, and its benzyl structure can enhance the affinity of the demulsifier for the oil phase and promote the demulsifier to penetrate into the oil-water interfacial film, destroying the stability of the film.

[0036] The above are only the preferred embodiments of the present invention and do not impose any form of limitation on the present invention. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments by using the disclosed technical content without departing from the technical solution of the present invention. However, any indirect modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention without departing from the technical solution content of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A preparation method of a demulsifier for oil exploitation, characterized in that, The preparation method includes the following steps: Step 1: Add silica to the mixed acid, stir while controlling the temperature, centrifuge, wash, and dry to obtain a pretreated product; the dosage ratio of silica to the mixed acid is 1.0 - 1.2 g : 25 - 30 mL; the mixed acid is composed of concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 1 : 0.5 - 1.5; Step 2: Stir and mix the silane coupling agent and ethyl acetate, add sorbic aldehyde to react, cool, centrifuge, place in absolute ethanol, add the pretreated product for ultrasonic dispersion, heat and stir, filter, wash, and dry to obtain an intermediate product; the silane coupling agent is N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane; the mass ratio of the silane coupling agent, ethyl acetate, sorbic aldehyde, absolute ethanol, and the pretreated product is 10 - 13 : 40 - 50 : 18 - 25 : 60 - 80 : 12 - 14; Step 3: Mix the intermediate product and water, stir at high speed, add acrylamide and benzyl methacrylate and stir, add the initiator and raise the temperature to stir, continue to raise the temperature to stir, cool down, adjust the pH, and granulate in a granulator to obtain the product; the mass ratio of the intermediate product, deionized water, acrylamide, benzyl methacrylate, and the initiator is 3.0 - 3.5 : 40 - 50 : 14 - 16 : 21 - 26 : 2.4 - 3.0; the initiator is composed of an oxidizing persulfate and a reducing sulfur-containing salt; the oxidizing persulfate is one or more of ammonium persulfate, potassium persulfate, and sodium persulfate; the reducing sulfur-containing salt is one or more of sodium bisulfite, sodium sulfite, and sodium thiosulfate.

2. The preparation method of a demulsifier for oil exploitation according to claim 1, characterized in that: In Step 1, the stirring while controlling the temperature is to stir at 30 - 50 °C for 2 - 3 h.

3. The preparation method of a demulsifier for oil exploitation according to claim 1, characterized in that: In Step 2, the reaction is to react at 50 - 62 °C for 4 - 6 h, the ultrasonic dispersion is to perform ultrasonic treatment at a power of 200 - 300 W for 30 - 45 min, and the heating and stirring is to stir at a temperature of 50 - 60 °C for 4 - 6 h.

4. The preparation method of a demulsifier for oil exploitation according to claim 1, characterized in that: In Step 3, the high-speed stirring is to stir at 1000 - 1200 rpm for 5 - 8 min, and the heating and stirring is to stir at 50 - 60 °C for 1.0 - 1.5 h.

5. The preparation method of a demulsifier for oil exploitation according to claim 1, characterized in that: In Step 3, the continued heating and stirring is to stir at 80 - 90 °C for 0.5 - 1.0 h, the cooling is to cool down to 40 - 50 °C, and the particle size after granulation is 1 - 2 mm.

6. A demulsifier for oil extraction prepared by the preparation method according to any one of claims 1 to 5.

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